The invention relates to a coupling for a medical instrument for connecting two lines, with a first coupling part, and with a second coupling part which can be inserted into the first coupling part in the longitudinal direction of the coupling parts, with first locking elements arranged on the first coupling part and second locking elements arranged on the second coupling part, the first locking elements being movable between a locking position, in which they engage with the second locking elements, and an unlocking position, in which they disengage from the second locking elements, and also with retaining elements which are arranged on the first coupling part and which are movable between a retention position, in which they keep the first and second locking elements in engagement with each other, and a release position, in which the first and second locking elements can be disengaged.
The invention further relates to a method for producing a first coupling part.
The expression “line”, for the purpose of the invention, refers to all types of tubular structures, but also to lines for electricity or light. Examples include lines for fluids, that is to say liquids or gases, such as for example flexible hoses or rigid pipes, instrument channels, and also electrical leads and light guides.
A coupling with the aforementioned structural features is known from German Utility Model DE 79 09 593 U1.
A coupling of the aforementioned type is generally used to connect two lines to each other. For this purpose, the first coupling part is or can be connected to a first line, and the second coupling part to a second line.
However, one of the two lines to be connected to each other can also be an attachment piece of a device, for example of a pump, in which case the first coupling part or the second coupling part is then secured or can be secured to the housing of the device.
An example of the use of the aforementioned coupling is for connecting an irrigation and/or suction hose to an irrigation and/or suction source for medical applications. For example, in surgical procedures, particularly in minimally invasive endoscope-assisted surgery, suction and/or irrigation instruments are used to irrigate the operating site and to remove liquids and/or tissues from the operating site. Such a suction and/or irrigation instrument is connected to the suction and/or irrigation source via a hose by means of the aforementioned coupling.
When the aforementioned coupling is used for a medical instrument, there are strict demands in particular on the ease of handling, its ability to be cleaned sufficiently and a compact size. It is desirable in particular for the two coupling parts to be able to be plugged together simply in the longitudinal direction of the coupling parts and as far as possible without a rotational movement.
The coupling known from the abovementioned German utility model is likewise used in the medical field, for example in dialyzers or oxygenators for blood.
In the known coupling, the first locking elements arranged on the first coupling part are in the form of six balls which are distributed circumferentially in the wall of the first coupling part and which are movable substantially transverse to the longitudinal direction of the coupling, that is to say in the radial direction. The second locking elements formed on the second coupling part are in the form of a groove which is present on the outer circumference of the second coupling part and which is limited in the longitudinal direction by two annular flanges.
The retaining elements in the known coupling are formed by a longitudinally displaceable sleeve which is arranged on the first coupling part and surrounds the latter on the outside. To connect the first coupling part to the second coupling part, the second coupling part is inserted into the first coupling part until the groove comes to lie level with the balls. When inserting the second coupling part into the first coupling part, the outer sleeve of the first coupling part must be drawn back manually into the release position against the force of a spring bias and must be kept in this position in order to ensure that the balls can move into their unlocking position upon insertion of the second coupling part. It is only after complete insertion of the second coupling part into the first coupling part, that is to say when the balls lie level with the groove, that the sleeve can be let go, which sleeve then moves into the retention position, on account of the bias, and keeps the balls in engagement with the groove, as a result of which the two coupling parts are held together in the longitudinal direction.
In order to separate the known coupling, the reverse procedure is followed, that is to say the sleeve is first drawn back from the retention position to the release position, after which the second coupling part can then be pulled manually out of the first coupling part, or the first coupling part can be pulled manually from the second coupling part.
Although the two coupling parts of the known coupling can be connected to each other without a rotational movement, a disadvantage of the known coupling is that, particularly upon separation of the coupling, when the first coupling part is pulled off from the second coupling part, considerable force has to be applied manually in order to disengage the balls from the groove, whereby the coupling parts may catch during separation of the coupling, particularly if the sleeve is not maintained securely in its release position when the first coupling part is being pulled off from the second coupling part.
Moreover, the seal provided in this coupling is arranged such that it can be accessed only with difficulty.
An object of the invention is therefore to develop a coupling of the aforementioned type in such a way that the smooth running of the coupling is improved, particularly during separation.
A further aim is to improve the access to the seal in such a coupling.
A further aim is to make production of the first coupling part easier.